Lionfish 101: Complete Care Guide 2020

Lionfish are a bizarre but striking species of marine fish that are well-known for their long dorsal spines that resemble the mane of a male lion.

They’re also considered one of the most venomous fish, so keeping this animal as a pet certainly has its risks.

If you’re thinking of owning the beautiful but venomous lionfish, then read on!

Here’s everything you need to know about this species, including diet, tank setup, tankmates, and breeding. 

Species

There are 12 recognized species of lionfish, but some of the most commonly studied ones are Pterois radiata, Pterois volitans, and Pterois miles. 

These fishes are popular in the aquarium trade due to their unique appearance, but they are considered an invasive species in the United States, specifically in Southeast and Caribbean coastal waters.

Why Are They Called Lionfish?

These fish are called lionfish due to their long, flowing dorsal spines and wide pectoral fins which are usually covered in white and red colors.

This majestic appearance resembles the mane on a male lion.

Origins

Lionfish are commonly found in the Indo-Pacific (both central and western Pacific oceans) and the Red Sea.

A few species of lionfish inhabit a wide range of areas, such as the Russel’s lionfish (Pterois russelli) which inhabits reef and rocky environments in tropical and subtropical waters.

They are located in many other areas, from western Australia and east Malaysia to French Polynesia and Pitcairn Islands (United Kingdom), north to southern Japan, and more.

Native Lionfish

Some lionfish have more limited ranges like the Hawaiian lionfish (Pterois sphex) which is a native species in and around the Hawaiian Islands.

The species has also been spotted in places that they are non-native in, including along the southeastern United States coast from Florida to North Carolina.

Young species have been reportedly seen in waters off New York, Long Island, and Bermuda.

NOTE

It’s thought that the lionfish populations in these areas are due to them being intentionally released in the Atlantic since their introduction into the aquarium trade.

Natural Habitat

The lionfish is found in nearly all marine habitat types.

They have been seen in water depths from 1 to 300 feet on mangrove, seagrass, coral, artificial reefs, and even the hard bottom.

Lionfish Swimming Near Seabed

Physical Appearance

Lionfish are easily distinguished by its fleshy tentacles above its eyes and below its mouth, long flowing dorsal fins, and broad pectoral fins.

They are brown or reddish in color, with white or black bands along their head and body. 

Lionfish are aposematic, which means they warn predators of their dangerous nature.

Their contrasting coloration and wide pectoral fins alert other creatures of their venomous spines.

How Do You Tell If They Are Male or Female?

Lionfish are difficult to sex as there aren’t any external differences between males and females.

The only time you can easily distinguish between male and female lionfish is during spawning.

Signs

When male lionfish are ready to mate, their coloration turns darker and their bands become less noticeable.

Females, on the other hand, turn a paler shade.

The mouth, belly, and throat on a female lionfish will also change to a silvery-white color.

The male circles the female during mating and the pair rise to the water surface.

After this, the female vibrates her fins and releases her eggs, while the male fertilizes them.

Colors

Lionfish don’t come in a huge amount of color variations, with most species having red, brown, maroon, or yellow shades with dark bands. 

Do Lionfish Spines Grow Back?

If a lionfish damages its dorsal spines severely or too close to the base, then it’s unlikely that they will grow back.

However, if a lionfish damages its fins, they should regrow as long as their tank’s water quality is good. 

How Big Do Lionfish Get?

The average adult size for a lionfish depends on the species, but most reach up to 18 inches.

Dwarf lionfish, on the other hand, only grow to around 6 inches. 

How Many Species of Lionfish Are There?

There are 12 recognized species of lionfish, but the most popular variety available in the aquarium trade is the Pterois Volitans lionfish (commonly known as the red lionfish).

Dwarf lionfish, however, include 4 to 5 members of the Dendrochirus genus.

Aquarium Varieties

All species of lionfish share similar characteristics, but some have slightly different colors and adult sizes.

Here are the most popular aquarium varieties of lionfish available.

  • Red Sea Lionfish (Pterois Cincta)
  • Andover Lionfish (Pterois Andover)
  • Spotfin Lionfish (Pterois Antennata)
  • Red Lionfish (Pterois Volitans)
  • Dwarf Lionfish (Dendrochirus brachypterus)
  • Hawaiian Lionfish (Pterois Sphex)
  • African Lionfish (Pterois Mombasae)
  • Russell’s Lionfish (Pterois Russelii)
  • Clear-Fin Lionfish (Pterois Radiata)

They can harm reef ecosystems as they are one of the top predators that compete for space and food with other native species that have been overfished. 

Some of these overfished species include snappers and groupers.

It’s also feared that invasive lionfish will endanger species like the algae-eating parrotfish, which is crucial for keeping corals healthy by keeping seaweed to a minimum. 

Steady Rise

Additionally, the United States’ invasive lionfish population is rising by the minute and increasing its native range.

This is due to lionfish having no known predators and being capable of spawning all year long.

In fact, female lionfish are able to release around 2 million eggs each year.

As you can see, the invasive lionfish is a huge issue in the United States and is beginning to populate other areas they aren’t native to, which will have a major negative impact on reefs and ecosystems across the world.

Why Are Lionfish Bad for the Reef?

Coral Reef

Lionfish are bad for the reef as they threaten native species and habitats in the United States Atlantic coastal waters, with their populations increasing in other areas.

This invasive species can cause mass extinctions of native animals and plants, decreasing biodiversity and competing with native organisms for resources in short supply

DID YOU KNOW?

Red Pteroi invasive lionfish are largely present in Atlantic waters and the Carribean sea.

In fact, Pterois Volitans make up 93% of the invasive lionfish population. 

Lionfish Invasion – Is It Illegal to Have a Lionfish?

All Pterois genus of Lionfish cannot be imported into the state of Florida.

Mail order Pterois and imported Pterois in Florida pet stores are strictly prohibited.

In fact, anglers, divers, and commercial harvesters are encouraged to remove invasive lionfish from Florida waters.

This ban has been implemented due to lionfish being an invasive species in Florida reefs and waters and to limit its negative effect on native wildlife and ecosystems.

Do Lionfish Make Good Pets?

Although lionfish can make a stunning addition to a marine tank, they don’t tend to make good pets.

Not only are these fish potentially dangerous due to their venom, but they are not a good fit for community tanks as they will eat smaller fish (or anything they can fit into their mouths!).

Can You Raise Them in Captivity?

Lionfish are very hard to breed in captivity.

The shortfin lionfish appears to be the only species that has been successfully bred in captivity. This means that almost all species available in the aquarium trade are wild caught. 

Clearfin Lionfish
Clearfin Lionfish

Are They Good for Beginners?

Lionfish are not the best saltwater species for beginners for a number of reasons.

Not only are lionfish highly venomous, but they can be difficult to feed and house in community tanks.

Some varieties are very sensitive to water parameters and are generally challenging to keep alive.

How Long Do They Live For?

Lionfish often live for 10 to 16 years in the wild, but they can live longer in captivity if they are well cared for.

As you can see, lionfish have pretty long lifespans, so owning one is a big commitment. 

Do They Die Easily?

Most species of lionfish are hardy and robust fish that can do well in captivity.

However, some varieties like the Mombasa lionfish are a little more sensitive and will quickly deteriorate if they are subjected to poor water conditions.

Symptoms of Being Stung By a Lionfish 

If you get stung by a lionfish, be prepared to experience a lot of pain.

Severe pain is almost immediate after being stung, alongside bruising, swelling, and redness in the area where the dorsal spines entered your skin.

Other Symptoms

Later on, you might experience shortness of breath or allergic reactions that can be either minor or extreme.

Signs of a severe allergic reaction include anaphylaxis, nausea, dizziness, fainting, and even temporary paralysis.

Pain

Pain from lionfish venom can last for a few hours and gradually decrease over 24 hours.

It can take up to 2 days for the pain to completely fade away. 

The length of time symptoms last for and their severity depends on how much venom was delivered, how deep the dorsal spines went into the body, how long ago you were stung, and your own sensitivity to lionfish venom.

What Do I Do If I Get Stung By a Lionfish?

Venomous Spines - FWC photo by Karen Parker
Venomous Spines – FWC photo by Karen Parker

If you get stung by a lionfish, examine the puncture wound and remove any spines that might be embedded in the area.

Try to control the bleeding and submerge the wound into hot water (as warm as you can tolerate) for at least 30 minutes.

Using Heat

As lionfish venom is protein-based, heat is the best method for treating it and reducing pain (which you will have a lot of!).

Heat neutralizes the venom and stops it from entering your bloodstream.

If you cannot submerge your hand into water due to where the wound is located, then apply a cloth soaked in hot water to the affected site.

Using hot packs or a hairdryer can also help relieve some of the pain, but don’t burn yourself in the process.

Medication

You can also take benadryl for the pain and ibuprofen to help reduce swelling.

Even though lionfish stings cause a lot of swelling, make sure you don’t apply cold compresses or ice until the pain has completely gone.

Doing so will make the pain worse and increase its duration.

NOTE

Home remedies like baking soda, vinegar, urine, etc., aren’t recommended for lionfish venom as they are not very effective against protein-based neurotoxins.

Can You Die From Lionfish Venom?

There are no known fatalities associated with lionfish venom, but shock, pain intensity, and potential issues or infection caused by an untreated puncture wound can make it a possibility.

However, the chances of a healthy adult dying from a lionfish sting is extremely low.

So, if you get stung by a lionfish, try not to panic and don’t automatically assume the worst.

What Do Lionfish Eat?

Wild lionfish populations from the United States, Indo Pacific, Caribbean Sea, and other areas feed on similar foods.

All species are carnivores, so their diet is entirely meat-based.

They feast on invertebrates and small fish.

It’s thought that members of the Dendrochirus genus primarily consume crustaceans, while Pterois lionfish feed more on fish.

Hunting

The majority of lionfish hunt for food at dusk or when it is dark.

For example, the spotfin lionfish comes from its hiding spot in the late afternoon to feed on shrimp and crabs.

Dinnertime for this species lasts well into the night. 

Pterois Volitans lionfish, on the other hand, tend to eat during the day. 

Group

Some lionfish will hunt together to increase their odds of securing a meal.

Groups of volitans lionfish will chase schools of baitfish up against the coral reef to corner off a few individuals for them to easily attack.

Appetite

Lionfish can eat fish and invertebrates that are over half their own length.

They consume more than 70 invertebrate and fish species, such as the parrotfish, banded coral shrimp, yellowtail snapper, and Nassau grouper. 

Additionally, they compete for food sources with native predatory reef fish like the snapper and grouper.

This is why the lionfish invasion in coastal waters across the globe is so problematic to coral reefs.

School of Small Fish
School of Small Fish

Aquarium Setting

In captivity, lionfish can be a little harder to feed due to their preference for live prey.

Initially, you may need to feed your lionfish live food before gradually transitioning them onto frozen and freeze-dried food. 

What Is the Best Food for Lionfish?

To keep your lionfish healthy, you should offer them a wide variety of foods.

A well-balanced diet for this species should include frozen silverside, krill, squid, and freeze-dried krill.

They can also be fed live ghost shrimp.

The latter are a good choice if your lionfish refuse to eat frozen or freeze-dried foods as they are much more nutritious than feeder fish like goldfish and rosy red minnows. 

Live Food

Feeder goldfish are commonly fed to lionfish, but this is not recommended.

The flesh of a raw goldfish contains thiaminase, which is an enzyme that causes the breakdown of thiamin.

Lionfish that primarily eat feeder goldfish are at risk of becoming thiamin deficient.

TIP

If your lionfish won’t eat frozen or freeze-dried food, then offer them ghost shrimp for 2 to 4 weeks. 

Fish Food Variety
Fish Food Variety

Feeding Frozen Food

You can encourage your fish to eat frozen and freeze-dried foods by using a piece of airline tubing.

Simply attach the food to the tube and wiggle it around in the tank water. This motion will help trigger your lionfish’s attack response.

How Should I Feed Lionfish?

When feeding your lionfish, make sure you steer clear of their pectoral fins and dorsal spines to avoid being stung.

While lionfish don’t tend to be aggressive towards humans, you still want to be on your guard. 

How Many Times a Day Should I Feed a Fish Lion?

Wild lionfish eat anywhere from one to over 10 small- to medium-size fish or invertebrates every day. However, in captivity, it’s best to feed them either 2 or 3 times a week.

A lot of this depends on your tank’s temperature as you might not need to feed your fish as much at lower temperatures.

Complications

If you overfeed your lionfish or don’t mix up their diet regularly, then fatty degeneration of the liver can occur.

This is a serious condition that can result in liver failure, leading to hemorrhaging, anemia, and suppression of the immune system. 

Avoid Large Prey

Additionally, you should avoid giving your lionfish large prey items as they could die from overeating.

Instead, offer your lionfish large portions of small prey items rather than a small portion of one large prey item.

Substrate

Lionfish are not great swimmers, so they tend to move by scurrying across the substrate, slowly rising and dropping the soft rays on their dorsal and anal fins.

It’s best to use a soft substrate like aragonite sand or crushed coral to avoid injury to your lionfish’s delicate dorsal and anal fins. 

Substrate To Avoid

I wouldn’t recommend gravel for a couple of reasons.

For one, it doesn’t offer any buffering capabilities like crushed coral or aragonite sand. And secondly, it might be a bit too rough and harsh for your lionfish to swim along.

Filtration

No matter what species of saltwater fish you own, it’s vital that you invest in a high-quality filter.

A powerful filtration will help keep your waters clean and provide your lionfish with a healthy habitat. 

Aquarium Water Bubbles
Aquarium Water Bubbles

Types of Filter

As some species of lionfish are sensitive to poor-quality waters, good filtration is key to their survival.

There are many types of aquarium filters to choose from, including HOB (hang-on-back) filters, canister filters, sponge filters, and internal filters. 

Ideal Filter

Personally, I’d recommend either a canister or HOB filter for keeping this invasive species in an aquarium

Lionfish don’t like a lot of water movement in their tank, so make sure their waters are slow and gentle.

Filters that have an adjustable flow rate will allow you to tweak the movement in your aquarium.

When choosing a filter for your red or Volitans lionfish, select a model with a suitable water flow rate for the size of your tank.

NOTE

As a rule, your filtration system should be able to clean at least four times the volume of your aquarium.

So, if you have a 50-gallon tank, then you’ll need a filter with a flow rate of at least 200 gallons per hour (GPH).

Heat

As lionfish come from tropical waters in areas such as the Indo-Pacific, Western Atlantic, Caribbean Red Sea, and North Carolina, they require warm water to survive.

To make sure their tank’s temperature is high enough, you’ll need a fish tank heater. 

There are a lot of different aquarium heaters you can choose for your tank, such as submersible heaters, immersible heaters, and substrate heaters. 

Lights

An aquarium light is another piece of equipment you’ll need for a lionfish tank. Unless you want to grow corals and live plants, any light will do the trick.

Most fishkeepers keep their aquarium lights on for between 8 and 12 hours each day.

Multicolored Light
Multicolored Light

Plants and Decorations

The majority of lionfish species are most active at dawn or dusk, so they will spend a large portion of their time hiding during the day.

Make sure your marine tank has plenty of caves, crevices, and covered rockwork so your fish has somewhere to retreat to during daylight.

This is especially true for Antennata and Radiata lionfish who almost exclusively only venture out at dark.

Dwarf lionfish, on the other hand, are much more adventurous.

These fishes will often be out and about during the day once accustomed to their tank.

Carnivores

Lionfish don’t do any damage to corals, but they aren’t exactly reef safe.

Lionfish will eat any invertebrates or fish that are smaller than them.

However, if your reef aquarium houses fish larger than your lionfish, you shouldn’t experience any problems.

Additionally, as lionfish are carnivores, they can be kept with live plants. 

What Size Tank Do They Need?

The recommended tank size for a lionfish depends on the type.

For example, the volitan lionfish needs to be kept in at least a 120-gallon marine aquarium as they can grow up to 15 inches.

However, members of the dwarf lionfish can be housed in tanks around 30 to 55 gallons as they reach around 6 inches in size. 

Housing Recommendations

Like any fish species, lionfish need specific water parameters to ensure their survival in home marine/reef aquariums. 

Salinity Level

As lionfish come from the ocean, they are saltwater fishes.

This means they require salinity in their aquarium. Ideally, your aquarium for this invasive species should have a specific gravity (sg) between 1.021 and 1.023.

Water Changes

Aquarium Water Change
Aquarium Water Change

Water changes are a vital part of keeping fish for ensuring a stable water chemistry.

If you don’t do proper maintenance on your marine/reef tank, then your fish’s habitat won’t be very healthy. 

Frequency

Uneaten food, fish waste, debris, and decaying plant matter will start to decompose and decrease the quality of your water without regular water changes. For most tanks, removing around 20% to 30% of water each week is usually sufficient. 

NOTE

However, the size of your tank and the stocking level of your marine/reef aquarium will influence this. If you have a small and overstocked tank, then you’ll need to perform water changes more than once a week.

Temperature

Lionfish inhabit tropical and subtropical waters, so their tank needs to be at an appropriate temperature.

You should aim to keep your lionfish marine/reef tank at around 72 and 78° F.

Water pH Level

Lionfish prefer their water slightly alkaline, with a pH between 8.1 and 8.4.

Carbonate hardness should be between 8 and 12 dkH. 

Maintenance

Like any pet, lionfish require time and work to keep happy and healthy.

Not only will your fish need feeding multiple times a day, but they will also need their tank cleaned (via water changes) at least once a week.

Additionally, you’ll need to check your aquarium equipment frequently to make sure it’s all working as intended, as well as examine your fish daily for signs of illness.

Last but not least, you’ll need to test the water in your marine tank regularly to make sure your water parameters are in order.

Lionfish can sting other fish, which can cause injury or death to the victim.

If threatened or scared, lionfish will charge at other fish with their dorsal spines to inject venom into them.

However, they tend to leave other fish alone unless they are picked on.

In this case, the lionfish is simply protecting itself from the bully.

Alternatively, lionfish can accidentally sting other tankmates if they get too close to their dorsal spines, such as during feeding.

Do Lionfish Eat Other Fish?

Lionfish will eat anything they can fit in their mouths, so they will prey on small fish and invertebrates.

In fact, lionfish even consume cleaner fish and cleaner shrimp that remove parasites and detritus from marine life. 

Compatibility

Due to their potent venom that can kill other tankmates, great care must be taken when choosing tankmates for these fishes.

Additionally, as they are carnivores, the invasive lionfish will make quick work of any small inhabitants in their reef aquarium.

What Fish Can You Keep with Lionfish?

Even though lionfish don’t often sting tankmates, it can still occur if they are provoked or even by accident.

There will always be this risk if you want to keep your lionfish in a community tank.

When choosing tankmates for your lionfish, opt for deep-bodied species like butterflyfish and angelfish.

Butterfly Fish
Butterfly Fish

Avoid Slow Tankmates

Puffers, other scorpionfish, and fishes that are slow swimmers are more likely to get stung as they aren’t very agile.

They won’t be able to quickly move out of the way of your lionfish’s pectoral fins and dorsal spines.

Avoid Smaller Tankmates

Avoid fishes that are smaller than your lionfish, as well as invertebrates.

As lionfish are carnivores, they will eat tankmates that are smaller enough to fit inside their mouths.

While they can be placed in reef tanks, you’ll have to make sure their other tankmates are bigger than them.

How Many Lionfish Should You Keep Together?

Lionfish can be kept together as long as your tank is large enough.

However, if you want to house multiple lionfish together, make sure all individuals are a similar size.

For example, avoid keeping dwarf lionfish with bigger species like the red lionfish as the former is likely to get eaten. 

TIP

Additionally, it’s best to add all individuals to your reef aquarium at once on the same day to avoid aggression. 

Can I Keep Just One Lionfish?

Lionfish aren’t overly social, so they can live alone quite happily.

If you want to keep more than one lionfish, make sure your aquarium is able to accommodate the size and bioload of multiple individuals. 

Health Concerns

Most lionfish species are hardy and relatively disease resistant, so they aren’t as prone to illness and disease as other species.

As long as their waters are kept healthy and clean, lionfish should thrive with very few problems.

That said, there are still a few aliments you should look out for to be on the safe side.

Signs of a Healthy Lionfish

A healthy lionfish will be relatively active, though bear in mind that most species will hide during the day.

Their eyes should be clear and alert, and they should be swimming without any abnormalities along the bottom of the aquarium. 

Additionally, your lionfish should have long, meticulous pectoral fins and dorsal spines.

TIP

To help your lionfish stay in good health, feed them every other day, give them a well-balanced diet, and keep their waters pristine. 

Red Flags

If your red lionfish is suffering from an illness or disease, then here are some symptoms you should look out for. 

Healthy Lionfish

Common Illnesses and Diseases

Marine Velvet

Marine velvet is one of the most common diseases that saltwater aquarists run into. It’s often transmitted via new individuals.

This is why you should properly quarantine any new inhabitants before you add them to your main tank.

The disease is caused by a single-celled organism (dinoflagellate) called Amyloodinium ocellatum, which is naturally present in most aquariums.

Unfortunately, this organism is very resilient and difficult to deal with.

Symptoms

If your red lionfish has marine velvet, they will usually have symptoms like inflamed or bloody gills, lethargy, and difficulty breathing.

They may also rub against tank decor in an attempt to rid themselves of the dinoflagellate. 

Once the disease has progressed, sufferers will often develop gold-colored spots on their body that give them a velvet-like appearance.

Prognosis

Sadly, once these spots appear, the gills are typically far too damaged for treatment to be successful. 

As the gills and lung tissue die off, sufferers will begin to lose the ability to transport oxygen to the gill membranes.

This usually leads to suffocation, followed by death.

Treatment

Marine velvet is lethal if it isn’t dealt with quickly, so you need to act fast if you suspect your red lionfish has it.

Copper medications are the only treatment that is effective for this disease.

Bear in mind that high doses of copper can kill aquatic life, so make sure you adhere to the manufacturer’s instructions.

Reproductive Capacity

Female lionfish can spawn every 3 to 4 days, with 15 to 13 thousand eggs per batch.

A single female is capable of laying up to two millions every year in warm waters, which is a staggering amount.

This is why the lionfish population is so large in the ocean, even in areas they are non native to. It’s also why Pterois volitans make up 93% of the invasive lionfish population. 

A male Pterois volitans can spawn with several females during breeding in warm waters.

Signs of Mating

Males will display darker coloration and less noticeable bands, whereas females will turn paler in general.

Spawning happens along the surface of the ocean water.

As the female releases her eggs, the male will fertilize them immediately.

The eggs hatch after 36 hours, at which point the larvae will stay in a pelagic state for up to 30 days.

Lionfish Front View
Lionfish Front View

Larva

The ocean current will scatter the larvae throughout the waters.

This process has helped the Pterois volitans lionfish population increase in the Atlantic and Carribean, which is why the species are so commonly found in those two locations. 

Larval Pterois volitans are excellent swimmers and will begin to feed on small ciliate protozoa.

They grow very quickly, as much as 1mm each day. 

Can They Breed in Captivity? 

Even though lionfish (especially Pterois volitans!) spawn rapidly in ocean waters, they are quite hard to breed in captivity.

The only species of lionfish that has been successfully bred in home aquariums is the dwarf shortfin lionfish. 

Conclusion

As long as you’re prepared to put in the work involved with owning a lionfish, they’re a fascinating species that can be a real beauty in a saltwater tank. 

Some of the most popular aquarium varieties include the spotfin lionfish, Pterois volitans (red lionfish), and red sea lionfish, but all species are visually striking.

Dwarf lionfish can live happily in 30-gallon to 50-gallon aquariums, but the red lionfish (Pterois volitans) and bigger species will need at least a 120-gallon tank. 

Handle With Care

As these fishes are capable of delivering venom via their spines, you need to be extremely careful when handling them and cleaning their habitat.

Being stung by this animal is incredibly painful, but there have been no known deaths associated with lionfish venom.

Diet

Lionfish need a lot of variety in their diet, so feed them a range of meaty foods like frozen krill, squid, silversides, and freeze-dried krill.

New specimens may need to be transitioned from live prey to frozen and freeze-dried foods. 

Housing

They can be housed in community tanks, but make sure you understand the risks involved. Although pterois volitans and similar species aren’t usually aggressive towards other tankmates of a similar size, they will attack if threatened. 

Small fish species and invertebrates are unsuitable in tanks that house lionfish (Pterois volitans, especially!) due to the species’ carnivorous nature.

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